The Impact of Acute Exposure to Cigarette Smoke on Airway Gene Expression

BACKGROUND: We have previously reported gene expression changes in the bronchial airway epithelium of active chronic smokers. In this study, we investigate the effects of Acute Smoke Exposure (ASE) from cigarettes on airway epithelial gene expression. METHODS: Bronchial airway epithelial cell brushings were collected via fiberoptic bronchoscopy from 63 individuals without recent exposure to cigarette smoke (> 2 days), at baseline and at 24 hours after smoking three cigarettes. RNA from these samples was profiled on Affymetrix Human Gene 1.0 ST microarrays. Differential gene expression was assessed using linear modeling and compared to previous smoking-related gene-expression signatures using Gene Set Enrichment Analysis (GSEA). RESULTS: We identified 91 genes differentially expressed 24-hours after exposure to three cigarettes (FDR < 0.25). ASE induces genes involved in xenobiotic metabolism, oxidative stress, and inflammation; and represses genes involved in cilium morphogenesis, and cell cycle. Genes induced by in vivo ASE are concordantly altered by ASE in vitro. While many genes altered by ASE are altered similarly in the airway of chronic smokers, metallothionein genes were induced by ASE and suppressed among chronic smokers. Metallothioneins were also suppressed in the bronchial airway of current and former chronic smokers with lung cancer relative to those with benign disease. CONCLUSIONS: Acute exposure to as little as three cigarettes alters gene-expression in bronchial airway epithelium in a manner that largely resembles the changes seen in chronic active smokers. The difference in the short-term and long-term effects of smoking on metallothionein expression and its relationship to lung cancer requires further study given these enzymes role in responding to oxidative stress.

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Billatos E, Faiz A, Gesthalter Y, LeClerc A, Alekseyev YO, Xiao X, Liu G, Ten Hacken NHT, Heijink IH, Timens W, Brandsma CA, Postma DS, van den Berge M, Spira A, Lenburg ME